The invention related to an integrated process wherein an air separation unit is integrated with a gas turbine and a unit consuming oxygen enriched air, such as a blast furnace.
The standard method for increasing the oxygen content of the blast sent to a blast furnace is to add relatively pure oxygen to a pressurised air stream. The oxygen comes from an air separation unit as described for example in U.S. Pat. No. 6,119,482, U.S. Pat. No. 5,244,489 and EP-A-0531182. In terms of energy, the cost of 1 Nm3/h of oxygen produced using a mixing column is 0,32 KWh/Nm3 of oxygen.
U.S. Pat. No. 4,962,646, U.S. Pat. No. 5,295,351, U.S. Pat. No. 5,268,019 and U.S. Pat. No. 5,317,862 describe processes in which air from the compressor of a gas turbine is fed to an air separation unit. The oxygen produced by the air separation unit is sent to a blast furnace.
U.S. Pat. No. 6,089,040 describes a process in which a blower supplies air to a blast furnace and to an air separation unit which, in turn, provides oxygen for the blast furnace.
Air is also sent to the air separation unit via a dedicated compressor and nitrogen from the air separation unit is sent to a gas turbine.
The present invention is intended to provide particularly low cost oxygen on a site where an air separation unit, a gas turbine and a blast furnace (or similar oxygen enriched air consuming unit) are present. Using the invention, the value of the oxygen in terms of energy falls below 0,2 KWh/ Nm3.
All pressures mentioned are absolute pressures, all percentages are molar percentages and enriched fluids are enriched in the component mentioned with respect to air.